She just cannot tape it. Why not? If she could take notes, if she could attend, if she could protest, why not tape it?
Was it a private meeting? No.
Was it on private property? No.
Was it during a non-public time? No.
So when is it against the law for a public meeting held on public property during a public time period to be video taped by a person who had every right to be there?
You can videotape a parade down main street, a public high school football game, a hot air balloon festival. So why is it illegal for a parent of a student at a public High School to tape a meeting that is open to parents and students on school ground during a school day?
It isn't.
The school policy that does not allow taping without the students' permission more than makes sense. Would you want your student being taped while in class or while they eat lunch or any other time without their permission. No, of course not. Parades, games and plays are very different. By participating in each of those, you are implicitly giving your consent to be watched and taped. Participation in classroom activities and small optional assemblies is very different and the school policy is there to protect the children. Your response is going to be that taping this and exposing it is protecting the children. Well perhaps, but the parents of the children involved had every right to a) stop it before it happened, b) attend, c) lodge a complaint after the fact. Taping it was simply not necessary and contrary to public policy.